Abstract
An equivalent short time annealing experiment was carried out to study the heating effect on heat-affected zone of Al-Zn-Mg alloys by welding. Mechanical properties and resistance to stress corrosion cracking were investigated after the annealing.
The results obtained in T4, T6 and T7 treated alloys were as follows:
(1) In T6 and T7 treated alloys, the recovery of strength was not clearly found by ageing treatment after the annealing at 250°C.
(2) After the annealing at above 350°C for only 1 min., the properties before the annealing was perfectly changed.
(3) It was confirmed that there was a close correlationship between the resistance to stress corrosion cracking and the structure of alloys aged after the annealing.
(4) The strength of the alloys was increased with the increase of cooling rate after the annealing. However, the stress corrosion resistance was increased with the decrease of cooling rate after the annealing.
